1. Field of the Invention
The present invention relates to a novel immunosuppressive agent. Specifically, the present invention relates to an immunosuppressive agent containing, as an effective ingredient, a sulfofucosylacylglycerol derivative. More specifically, the present invention relates to an immunosuppressive agent containing, as an effective ingredient, sulfofucosylmonoacylglycerol, i.e., 3-0-(6-deoxy-6-sulfo-α/β-D-galactopyranosyl)-1-0-acylglycerol and/or sulfofucosyldiacylglycerol, i.e., 3-0-(6-deoxy-6-sulfo-α/β-D-galactopyranosyl)-1,2-0-diacylglycerol}.
2. Description of the Related Art
In clinical treatment presently performed, transplantation can be employed to treat chemotherapeutically untreatable diseases. Transplantation is the technology for treating a disease by replacing partly or entirely of a diseased organ with a healthy organ taken from another individual. Organ transplantation has been performed with respect to a wide variety of organs such as kidney, liver, lung, intestine, heart, pancreas, and cornea. The number of organ transplantations has been increased.
The immune response of skin is inherently high. However, skin transplantation can be made successfully if a graft skin transplanted from one person to another can be kept alive for at least a few weeks. This is because new dermal tissue, if a graft epidermis is kept alive for a few weeks, can regenerate itself, thereby recovering from a dermal tissue damage. Therefore, it is possible to make physical recuperation of serious and extensive burn or laceration by transplanting a dermal tissue from another person.
The most fearful problem residing in tissue or organ transplantation is a rejection caused by a recipient's immune response.
Under these circumstances, in order to develop an immunosuppressive agent capable of preventing the rejection in a recipient, thereby attaining permanent fixation of a transplanted organ, intensive studies have been conducted since the 1970s, particularly in European countries and U.S.A.
On the other hand, an immunosuppressive agent may also be important in treating autoimmune diseases such as rheumatism and collagen disease, since it can mitigate the symptoms to a certain degree.
Up to the present, cyclosporin A and FK506, etc., have been developed as immunosuppressive agents. However, the functional mechanisms of these immunosuppressive agents resemble each other and their chronic toxicity is a matter of concern. Thus, to attain prolonged life in next-generation organ transplantation, another type of immunosuppressive agent is desired which has a lower toxicity based on a different chemical structure, and thus, different functional mechanism can be expected.
It has been found that naturally-occurring sulfur-containing glycolipids have pharmaceutical activities such as an anticancer effect (Sahara et al., British Journal of Cancer, 75(3), 324-332, (1997)); inhibitory activities against DNA polymerase (Mizushina et al., Biochemical Pharmacology, 55, 537-541 (1998), Ohta et al., Chemical & Pharmaceutical Bulletin, 46(4), (1998)); and HIV suppressive effect (National Patent Publication No. 5-501105). However, it has not yet been found that a sulfur-containing glycolipid, in particular, a sulfofucosylacylglycerol derivative, has an immunosuppressive activity.